JERUSALEM (JTA) — Teva Pharmaceuticals said its president and CEO, Jeremy Levin, has stepped down.

Levin reportedly resigned Wednesday, effective immediately, after 18 months on the job due to major differences with Teva’s chairman, Miami billionaire Phillip Frost, and the board of the world’s largest generic drug manufacturer.

But Levin told Israel’s Channel 10, “I did not resign. I did not choose to leave the company.”

Teva, which is based in Petach Tikvah, announced two weeks ago that it was cutting 5,000 jobs. Its board appointed chief financial officer Eyal Desheh as Levin’s interim replacement and has set up a search committee to find a permanent successor.

Levin was overseeing the company’s reorganization in preparation for the expiration of patents protecting its multiple sclerosis drug Copaxone, which will open it up to more competition on its best-selling product.

Among the employees worldwide set to be let go were 800 in Israel, which caused recriminations from the Israeli government and Histadrut labor union. Israel said it had supported Teva with subsidies and tax breaks, and the union insisted that the layoffs be spread out over time, which Levin agreed to against the board’s wishes.